Liebig Undercut Anchors
What makes them different
A mechanical interlock – not just friction
Standard expansion anchors rely on outward pressure against the drill hole wall. That pressure creates radial stress in the concrete, and under vibration or dynamic loading, holding capacity degrades. Liebig undercut anchors operate differently: a void forms in the concrete, and the anchor mechanically locks into it.
Mechanical interlock
Load transferred through positive form fit into concrete — independent of expansion pressure
Closer edge distances
No outward expansion force means smaller base plates and closer edge installations are possible
Visual confirmation
Domed washer flattens at the correct torque – No load testing needed.
Modular sizing
Any embedment depth, any bolt length — Liebig undercut anchors are manufactured to your project spec
Load transfers into the concrete substrate — not against the hole wall.
The technical difference
Expansion vs undercut Anchors: what actually happens under load
Understanding the load transfer mechanism is the key to specifying the right anchor for high-load, vibration-prone or safety-critical applications.
Conventional Expansion Anchors
- Load transferred through expansion pressure – Relies on friction against the drill hole wall.
- Performance under vibration – Micro-cracking reduces holding capacity over time.
- Concrete limitations – Many products are approved only for specific conditions.
Liebig Undercut Anchors
- Mechanical Interlock – Positive load transfer independent of expansion pressure.
- Simple Installation – Superplus BLS self-undercuts using a standard rotary hammer.
- ETA Option 1 – Approved for cracked and non-cracked concrete.
For safety-critical infrastructure subjected to vibration, heavy loads or demanding service conditions, undercut anchors provide a more reliable load transfer mechanism than anchors relying solely on expansion forces.
Why engineers specify Liebig
Certified for the applications that matter
Every Liebig anchor is assessed and certified – giving structural engineers, safety officers and project managers the documented load data they need to specify with confidence.
Learn More
Explore the Liebig Anchoring playlist on Youtube
Watch the Undercut Anchor video playlist here to explore all product showcases of the Liebig concrete support anchor range
Engineering Support
Speak with an Anchor Specialist
Whether you’re designing a new processing plant, upgrading existing infrastructure or selecting anchors for a safety-critical application, our engineering team can help. We’ll recommend the right anchor, provide technical documentation and assist with product selection based on your application, substrate and load requirements.
✓ Product Selection
✓ Load Advice
✓ Installation Guidance
✓ Project-Specific Solutions
Sam Smith
Commercial Development Manager — Anchoring Systems
No project is too early. If you’re still evaluating options, we’re happy to discuss your application before specification.